Editorial: Searching the galaxy for alien life continues

Russia's booster rocket Soyuz-FG is shown with the space capsule Soyuz TMA-11M that will carry new crew to the International Space Station, with US and Japanese national flags in the foreground at the launch pad. For the first time, it will also carry an Olympic torch to space as part of the ongoing Olympic torch relay. The torch will be brought back along with the station's current crew.

“Where is everybody?” Enrico Fermi famously asked 63 years ago. His question was cosmic: Our modest little eight-planet solar system is part of the Milky Way, which has at least 100 billion stars. The Milky Way, in turn, is one galaxy among 100 billion or more. The math suggests we should have seen signs of other civilizations by now.

What’s more, according to a study published this week, billions of those planets are potentially amenable to life as we know it. The nearest one could be just 12 light-years away.

So it’s tempting to reframe Fermi’s question slightly. Isn’t it possible, as we learn more about the cosmos, that Trekkies, alien abductees and UFO conspiracy theorists were right all along? Which is to say, it is more rational to believe in alien life than it is to not believe in it.

Not so fast, Mr. Spock. The new study, by astronomers from the University of California at Berkeley and the University of Hawaii, extrapolates from data collected by NASA’s Kepler Space Telescope. Yet this analysis, as exciting as it is, doesn’t mean that the existence of alien life is necessarily any more likely.

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Scientists still don’t know exactly why, or by what mechanism, life arose from nonlife on Earth, or how it would do so on any other planet. Until that process is better understood, the odds of it happening more than once remain anyone’s guess — no matter how many other Earths or near-Earths we find.

Still, as the search goes on, the prospect of discovering alien life has only become more tantalizing. Only a generation ago, the scientific community was almost unanimously dismissive of the idea. Today, it’s alive with theories about alien communication, alien biochemistry, alien conquest. (Really: That last theory comes from none other than Stephen Hawking.) Astronomers around the world are working on techniques to parse radio signals, light pulses, even encoded neutrinos in search of a flicker of evidence suggesting cosmic intelligence.

That’s where this new study could prove quite useful. Although no one knows how life emerges, the Earth still offers the best model we have — the only model, in fact. The astronomer Jill Tarter has compared the search for alien intelligence to dipping a water glass in the ocean looking for fish. The Kepler data can help focus that search to planets where emergent life seems most probable. And it provides a crucial variable in the Drake Equation, which astronomers have long used as a kind of shorthand to determine how many intelligent civilizations might exist elsewhere in cosmos. In other words, it gives us a place to start.

Fermi’s question remains unanswered. But it only grows more compelling, and more perplexing, with each new discovery.